The placement of Gyrodactylus salmonis (Yin & Sproston) in the molecular phylogeny of studied members of the Gyrodactylus wageneri-group parasitizing salmonids.

The molecular phylogeny of Gyrodactylus salmonis from brook charr, Salvelinus fontinalis, rainbow trout, Oncorhynchus mykiss, cutthroat trout, O. clarkii, and Atlantic salmon, Salmo salar, in Canada is presented using sequences from ITS-rDNA and the mitochondrial COX 1 gene. Sequence variation among G. salmonis specimens from the different North American hosts was consistent with within-species variation reported for other Gyrodactylus. Sequence data are compared to those from other members of the wageneri group parasitizing salmoniform fishes in northern Europe (G. derjavini, G. derjavinoides, G. lavareti, G. salaris, G. salvelini, G. teuchis and G. truttae) and Asia (G. brachymystacis). Sequence divergence between G. salmonis and the recently described G. salvelini on Arctic charr, Salvelinus alpinus, in Finland was consistent with within-species levels of variation in Gyrodactylus; however, phylogenetic analyses and morphological comparisons provided evidence of their distinctiveness such that they appear to be sister species. They grouped with G. lavareti (a parasite of a coregonid) to form a clade separate from European and Asian species of the wageneri lineage known from salmonid fish. Further study of gyrodactylids from across salmonid, coregonid and thymallid fish in the northern hemisphere would shed more light on the phylogeography of these parasites and serves as an important backdrop to understanding the evolution of their emergent virulence.

A new integrative framework for large-scale assessments of biodiversity and community dynamics, using littoral gastropods and crabs of British Columbia, Canada.

Improving our understanding of species responses to environmental changes is an important contribution ecologists can make to facilitate effective management decisions. Novel synthetic approaches to assessing biodiversity and ecosystem integrity are needed, ideally including all species living in a community and the dynamics defining their ecological relationships. Here, we present and apply an integrative approach that links high-throughput, multicharacter taxonomy with community ecology. The overall purpose is to enable the coupling of biodiversity assessments with investigations into the nature of ecological interactions in a community-level data set. We collected 1195 gastropods and crabs in British Columbia. First, the General mixed Yule-coalescent (GMYC) and the Poisson Tree Processes (PTP) methods for proposing primary species-hypotheses based on cox1 sequences were evaluated against an integrative taxonomic framework. We then used data on the geographic distribution of delineated species to test species co-occurrence patterns for nonrandomness using community-wide and pairwise approaches. Results showed that PTP generally outperformed GMYC and thus constitutes a more effective option for producing species-hypotheses in community-level data sets. Nonrandom species co-occurrence patterns indicative of ecological relationships or habitat preferences were observed for grazer gastropods, whereas assemblages of carnivorous gastropods and crabs appeared influenced by random processes. Species-pair associations were consistent with current ecological knowledge, thus suggesting that applying community assembly within a large taxonomical framework constitutes a valuable tool for assessing ecological interactions. Combining phylogenetic, morphological and co-occurrence data enabled an integrated view of communities, providing both a conceptual and pragmatic framework for biodiversity assessments and investigations into community dynamics.

Effects of signal-to-noise ratio on the auditory brainstem response to 0.5 and 2 kHz tone bursts in broadband noise and highpass noise or notch noise.

This study investigated the effects of signal-to-noise ratio (S/N) on the latency and amplitude of th3 auditory brainstem response (Wave V) using 0.5 and 2 kHz tone bursts in highpass/notch noise and broadband noise. Normal listeners were presented with 40 and 80 dB nHL tone bursts in quiet and in noise at S/Ns of 10, 15, 20, and 25 dB. The latency data suggest that, at moderate and high intensities, highpass/notch noise or broadband noise is preferred to the quiet condition because of the improved frequency specificity provided by the masking. Highpass/notch noise appears preferable to broadband noise when testing at moderate to high levels because the former produced larger Wave V amplitudes to 0.5 and 2 kHz tone bursts at 80 dB nHL. The 80 dB nHL data also suggest that S/Ns of 15-25 dB should be selected when the highpass/notch noise is mixed with moderate to high level 0.5 and 2 kHz tone bursts. In contrast to the 80 dB nHL data, Wave V amplitudes to the 40 dB nHL tone bursts suggest that testing in quiet may be preferred to testing in noise when 0.5 and 2 kHz tone bursts are presented at low levels. This is because of the simplicity of instrumentation and because larger amplitudes were observed in quiet than in noise.